We have reported (Environmental Research 11:66-77, 1976) that chronic 3- and 6-month exposures of rats to near-TLV concentrations of methyl methacrylate vapor in air are associated with changes in body weights, blood chemistries, and intestinal motor activities. We intend to determine: a) the most economical exposure regimen necessary to produce these effects, b) the age dependency of the effects observed, c) the possible interactions between exposure and intestinal absorptive function, and b) the effects of exposure upon the total lipid profile.